IAP my_app_user_id applicability scope

Hi.

Referring to in-app-purchases (IAP), e,g, videos like this one:

I have some questions regarding IAP.

  • Should IAP be valid across multiple devices for the same AppleID? I know I can do both, but what is common practice?
  • What do you take as my_app_user_id in either case (Device linked, AppleID linked)?

My app doesn’t have a user account system. RevenueCat changed their sample instantiation code recently as to include (optional) my_app_user_id. This would avoid that a deleted/reinstalled app will lose the IAP.

Many thanks,